Brake applying means



May 1, 1945. A.l o .wlLLlAMs BRAKE LAPPLYING' MEANS Filed Nov. 15, 194s Patented May l, 1945 f UNITED .STATES PATENT* oFFlcei v to `Clark `Equipment Company, .i Mich., av corporation of Michigan Application November 13, 1943, Serial'No. 510,224

l a. `(Clust-15s) This invention relates to brake applying"means,l

4.SClaima L and more particularly is concerned with electrie cally controlled means for applying a brake to a'revolving' member such asa drum, the tread of a rail car wheel, or the like;

The primary object of the present invention is to provide means for oontrollingthe amount of pressure to beapplied by the brake from zero to the highest maximum pressure desired.

In` former rail oar tread brakes and similar constructions, the" design has always been such I that the brake was eitherfully` oi or fully on,

and the operator had `no control over the rate of application of the brake or the amount of pre`s`- sure or braking action desired. The presentinvention therefore contemplates a design in which the brake can Abe gradually `appliedftothe .braking surface underthecontrol of the operatorand can bequickly released from any braking action by the operator.

In a preferred forni of the present invention this is accomplished by the use of a motor driven pump, the `pressure developed by the pump `being in direct proportion to the speed ol the motor and the vmotor speed being controlled manually by the operator. l

Another advantage of the present invention is the simplicity of construction and the fact that the mechanism can be mounted in any convenient place on the rail truck or undercarriage of the vehicle and may be operated from any reiliotely disposed point. l 1

Other objects and advantages of the present invention will appear more fully from the following detailed description which, taken in conjunction with the accompanying drawing, will disclose to those skilled in the art the particular construction and operation of a preferred form of the present invention.

The drawing is an elevational View, partly in section, or' one embodiment of the present invention.

Referring now in detail to the. drawing, there is shown a revolving brake surrace 5, which may be a drum or can be the tread of a rail car wheel or the like.

Mounted inposition to engage the annular surface of the member is a brake shoe 6, pivotally mounted as at l upon a brake applying arm 8. The arm 8 is pivotall;r supported on its lower end on the pivot 9, which is anchored into position yby the member II). At its upper end the arm t has the link I2 pivotally connected thereto, which `link I2 at its` opposite end is connected to the rod I3 extending into the piston Buchanan, l

i chamber |4` formedm the body nuernber-` i5.

Within the chamber Ill the rod I3 is provided` with an enlarged head or piston I6 operating within the cylindrical chamber I`4`and normally held inthe position shown bymeans of the coiled spring I'I. The eiidof the 'chamber` I4 is closed by a cap member i I 8 which is provided with a suitable packing gland I9fcr preventing loss Aof iiuidr along the surface ofthe rod I3 where'it projects from the piston body.- l A The lower part of the body member I5 is provided with asump `2l) within which is disposed iluid 22,` such as oil orthe like. l Mounted in the sump 20 is "a pump member 23 `which is preferably disposed below tne levelof the oil 22fand has an outlet 24 leading up to the forward end or the cylinder I4. The 'pump 23 is of the rotary typekand is driven byineans of a suitable 'direct current electric `motor 25, secured as by the flange l 26 to the side wall of the sump 2U. i

The motor hasone of its terminals connected through the conductor 2l and the coil 28 to a series of taps 29 forming a selective resistance coil adapted to beV engaged by the contact end 3c of a manually operated control lever 32 which is pivotally mounted as at 33. The control lever 32 is connected in the motor circuit through the conductor 34 to one side of a battery 35, the opposite side of the battery being connected through conductor 36 and fixed resistance 3l to the opposite terminal of the motor 25.

In the construction as thus far described, the operator moves the control lever 32 from the oir position indicated at 38 along the various taps Z9 of the variable resistance 4U. As the tip of the lever 32 contacts the respective taps, moving in a counterclockwise direction, the speed. of the motor is progressively increased. This results in increased speed of rotation of the pump 23 and thus increases the pressure developedby the pump, which is transmitted through the outlet 24 to the head of the piston I6, thereby moving the piston against tne spring pressure to apply thebrake against the braking surface 5. Thus the operator nas selective control of trie amount or pressure which he desires to apply against the braking surface `Upon returning o1' the control lever 32 to its on position, trie pump stops and trie pressure in tile nead end oi; the cylinder w against the piston lu is dissipated tiirougn the metering' orince w., controlled by the needle valve es; however, it is desirable that in some cases the pressure be released quickly and for this reason, I have provided the coil 2B in the motor circuit, which coil is in the form of a solenoid, having the armature 44 which, Whenever the coil is energized, is held iirmly against seat 45 formed in the outlet passage-way 46. 'I'hus this passage-way 46 is closed against the escape of fluid when the coil 28 is energized, but when the coil is de-energized, the uid pressure upon the end of the armature forces the amature upwardly to provide a quick release thereof through the passage-way 46 and the return conduit 4'I into the sump 20 of the body member I5. 'Ihe armature 44 also provides means for preventing too high a pressure being developed within the cylinder I4, acting in this manner as a safety releasevalve. This can be controlled by the windings of the solenoid to determine at which point the armature will be forced upwardly in spite of ythe holding action of the coil 28. I

Preferably a return port 48 is provided for return of iiuid which has passed by the piston I6 in the chamberv I4, the port 48 draining from the outlet end of I4 'back into the sump 20.

Due `to thecharacteristics of a direct current motorl in whichthe speed is directly controlled bythe potential impressed thereon, it is obvious thatthe pressure developed vby the pump 23 canbe controlled accurately by varying the resistance 40, This is done by the means of a control lever so that varying Yamounts of iluid pressure can be developed whereby the operator can accurately control the amount of pressure by the brake shoe 6 against the brakingsurface 5.

While it is apparent that, if so desired, the solenoid 28 and armature 44 could be eliminated and the entire return of fluid b e controlled through the metering oriiice 32, itis desirable in. certain circumstances to provide for quick release of the brakes and this can be readily accomplished by the use of the solenoid controlled relief valve.

It is therefore .believed apparent that I have provided a, simplified type of brake control for applying brakes in a vehicle which is of sturdy design and is easily controlled. I am aware that certain changes may be made in details of the present construction and I, therefore, do not intend to be limited except as defined by the scope and spirit of the appended claims.

I claim:

1. In combination, a, fluid controlled piston, brake means actuated thereby, a fluid pump of the positive displacement type, a variable speed motor for driving said pump to produce a predetermined uid pressure against said piston, a control circuit for said motor, a solenoid in said circuit, a valve normally held closed by said solenoid, subject to said uid pressure and providing for quick release thereof when said motor circuit isV decnergized.

2. The combination of claim 1 including ametering relase valve for said fluid pressure operating independently of said quick release valve.

3. In combination, a iluid reservoir having a cylinder formed therein above the lluid level, a brake-actuating piston Iin said cylinder, a pump in said reservoir below the fiui'dlevel and having its pressure side` connected to said cylinder. a passageway from said cylinder back into said reservoirI a valvein said passageway subject to uid pressure in Said cylinder, a solenoid coil adapted to hold said valve closed when energized. a motor for driving said pump, and a control circuit for said motor and solenoid whereby upon opening of said circuitsaid valve releases the fluid under pressure in said cylinder.

ALFRED O. WILLIAMS. 

